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The Life History and Contributions to the Ecology of Camelobaetidius variabilis Wiersema 1998 (Ephemeroptera: Baetidae) in Honey Creek, Oklahoma (open access)

The Life History and Contributions to the Ecology of Camelobaetidius variabilis Wiersema 1998 (Ephemeroptera: Baetidae) in Honey Creek, Oklahoma

A study of the life history and ecology of Camelobaetidius variabilis was conducted in Honey Creek, OK from February 2003-April 2004. Nymph development was assessed using changes in external morphology. Laboratory reared nymphs were used to calculate number of degree days to complete development (772 degree days at 20.8° C ±.38° C), which was used to determine voltinism. Field collected nymph microhabitat distribution was used in assessing microhabitat distribution. Nymphal thermoregulation was assessed during the winter and spring by comparing nymphal numbers present in shaded and un-shaded habitats. Camelobaetidius variabilis nymphs showed preference for algal microhabitats during the spring and leaf packs in the winter. Nymphs inhabited leaf packs to increase metabolic rate during the winter. Increased temperatures aid in development of nymphs. Camelobaetidius variabilis exhibited a multivoltine life cycle with six overlapping generations.
Date: December 2005
Creator: Perry, Heather A.
System: The UNT Digital Library
Mutation of Polaris, an Intraflagellar Transport Protein, Shortens Neuronal Cilia (open access)

Mutation of Polaris, an Intraflagellar Transport Protein, Shortens Neuronal Cilia

Primary cilia are non-motile organelles having 9+0 microtubules that project from the basal body of the cell. While the main purpose of motile cilia in mammalian cells is to move fluid or mucus over the cell surface, the purpose of primary cilia has remained elusive for the most part. Primary cilia are shortened in the kidney tubules of Tg737orpk mice, which have polycystic kidney disease due to ciliary defects. The product of the Tg737 gene is polaris, which is directly involved in a microtubule-dependent transport process called intraflagellar transport (IFT). In order to determine the importance of polaris in the development of neuronal cilia, cilium length and numerical density of cilia were quantitatively assessed in six different brain regions on postnatal days 14 and 31 in Tg737orpk mutant and wildtype mice. Our results indicate that the polaris mutation leads to shortening of cilia as well as decreased percentage of ciliated neurons in all brain regions that were quantitatively assessed. Maintainance of cilia was especially affected in the ventromedial nucleus of the hypothalamus. Furthermore, the polaris mutation curtailed cilium length more severely on postnatal day 31 than postnatal day 14. These data suggests that even after ciliogenesis, intraflagellar transport is necessary …
Date: August 2005
Creator: Mahato, Deependra
System: The UNT Digital Library
Mouse cortical cholinergic neurons: Ontogeny of phenotypes in vivo and in vitro. (open access)

Mouse cortical cholinergic neurons: Ontogeny of phenotypes in vivo and in vitro.

The development of cholinergic neurons in mouse frontal cortex was studied both in vivo and in vitro by immunocytochemistry with an antibody to choline acetyltransferase (ChAT), the enzyme responsible for acetylcholine synthesis. While cortical cholinergic neurons have previously been characterized in rat cortex, up until very recently, intrinsic cortical cholinergic neurons were considered to be absent in mouse, and little is known about their development or phenotypic characteristics. The present study found no ChAT-positive neurons in mouse frontal cortex on postnatal day 0 (P0, the day of birth). On P7 there were few, faintly stained, ChAT-positive neurons. The numerical density of ChAT-positive neurons increased substantially with age, from none on P0, to 9.2 + 1.4 on P7, to 14.8 + 0.9 on P16, and 41.6 + 3.9 in adulthood. Considering that the numerical density of total neurons decreases during this postnatal period, the data represent a marked developmental increase in the percentage of cholinergic neurons. The development of cholinergic neurons showed very similar timelines in rat and mouse frontal cortex. Cultures prepared from mouse frontal cortex on embryonic day 16 were maintained for 25, 76, or 100 days in vitro (div). The percentage of ChAT-positive neurons was considerably higher than …
Date: August 2005
Creator: Coiculescu, Olivia Elena
System: The UNT Digital Library
Functional and Categorical Analysis of Waveshapes Recorded on Microelectrode Arrays (open access)

Functional and Categorical Analysis of Waveshapes Recorded on Microelectrode Arrays

Dissociated neuronal cell cultures grown on substrate integrated microelectrode arrays (MEAs) generate spontaneous activity that can be recorded for up to several weeks. The signature wave shapes from extracellular recording of neuronal activity display a great variety of shapes with triphasic signals predominating. I characterized extracellular recordings from over 600 neuronal signals. I have preformed a categorical study by dividing wave shapes into two major classes: (type 1) signals in which the large positive peak follows the negative spike, and (type 2) signals in which the large positive peak precedes the negative spike. The former are hypothesized to be active signal propagation that can occur in the axon and possibly in soma or dendrites. The latter are hypothesized to be passive which is generally secluded to soma or dendrites. In order to verify these hypotheses, I pharmacologically targeted ion channels with tetrodotoxin (TTX), tetraethylammonium (TEA), 4-aminopyridine (4-AP), and monensin.
Date: May 2005
Creator: Schwartz, Jacob C.
System: The UNT Digital Library
The stonefly genus Isogenoides Klapálek (Plecoptera: Perlodidae) of North America: Systematics, behavior and ecology. (open access)

The stonefly genus Isogenoides Klapálek (Plecoptera: Perlodidae) of North America: Systematics, behavior and ecology.

The stonefly genus Isogenoides is revised following a holomorphological approach utilizing traditional morphology and behavioral lines of evidence. Species keys are provided for all life stages. One species, I. krumholzi (Ricker) is considered a synonym of I. doratus (Frison). Detailed species descriptions are provided for males, females, nymphs and ova. Distributions are updated utilizing all known published accounts and materials examined. The vibrational communication (drumming) behavior is reported for males and all but one species for females. The signals were species-specific and ranged in complexity from ancestral sequenced duets to derived grouped exchanges. I. olivaceus is least specialized, having mostly sequenced duets, and I. zionensis most specialized, displaying ancestral sequenced, derived grouped and complex derived exchanges containing both sequenced and grouped elements. Laboratory egg incubation experiments over a 2-4 year period show that Isogenoides has a great capacity for extended, sometimes-asynchronous diapause and hatching. The eggs of six species were incubated at a single, ca. simulated San Miguel River, Colorado, seasonal temperature regime. Direct hatch within two weeks occurred only for I. zionensis (Leopard Creek, Colorado) with small numbers hatching again after one, two, and four years. Eggs of I. doratus and I. varians hatched after an over summer, 3-5 …
Date: May 2005
Creator: Sandberg, John Burton
System: The UNT Digital Library